1. Technical Field of the Invention
The present invention relates to cosmetic or dermatological compositions for topical application, more particularly in a regime or regimen for photoprotecting the skin and the hair, comprising, in admixture, a UV-screening agent of the dibenzoylmethane derivative type and a 4,4-diarylbutadiene compound.
The present invention also relates to a process for improving the stability towards UV radiation of at least one dibenzoylmethane derivative, which entails combining with said dibenzoylmethane derivative, an effective amount of at least one 4,4-diarylbutadiene compound.
2. Description of Background/Related/Prior Art
It is known that light radiation with wavelengths of between 280 nm and 400 nm permit tanning of the human epidermis and that light rays with wavelengths more particularly between 280 and 320 nm, known as UV-B rays, cause skin burns and erythema which can harm the development of a natural tan. For these reasons, as well as for aesthetic reasons, there is a constant demand for means of controlling this natural tanning in order thus to control the color of the skin; this UV-B radiation should thus be screened out.
It is also known that UV-A rays, with wavelengths between 320 and 400 nm, which cause browning of the skin, are liable to induce adverse changes therein, in particular in the case of sensitive skin or skin which is continually exposed to solar radiation. UV-A rays cause in particular a loss of elasticity of the skin and the appearance of wrinkles leading to premature aging of the skin. They promote triggering of the erythemal reaction or amplify this reaction in certain individuals and may even be the cause of phototoxic or photoallergic reactions. Thus, for aesthetic and cosmetic reasons such as the conservation of the skin's natural elasticity, for example, an increasingly large number of individuals wish to control the effect of UV-A rays on their skin. It is thus desirable also to screen out UV-A radiation.
In this respect, one particularly advantageous family of UV-A screening agents currently consists of dibenzoylmethane derivatives, and in particular 4-tert-butyl-4′-methoxydibenzoylmethane, which have high intrinsic absorbing power. These dibenzoylmethane derivatives, which are products which are now well known per se as screening agents that are active in the UV-A range, are described in particular in FR-A-2-326,405 and FR-A-2-440,933, as well as in EP-A-0-114,607; 4-tert-butyl-4′-methoxydibenzoylmethane is moreover currently sold under the trademark “Parsol 1789” by Hoffmann LaRoche.
Unfortunately, it is found that dibenzoylmethane derivatives are products that are relatively sensitive to ultraviolet radiation (especially UV-A), i.e., more specifically, they have an annoying tendency to degrade more or less quickly under the action of this radiation. Thus, this substantial lack of photochemical stability of dibenzoylmethane derivatives towards ultraviolet radiation, to which they are by nature intended to be subjected, does not make it possible to ensure constant protection during prolonged exposure to sunlight, and as a result repeated applications at regular and close intervals must be made by the user in order to obtain effective protection for the skin against UV rays.
EP-0-967,200, DE-197,46,654, DE-197,55,649, EP-1-008,586, DE-100,07,017, EP-1-133,980 and EP-1-133,981 disclose antisun compositions based on 4,4-diarylbutadienes, which may contain other additional screening agents, such as dibenzoylmethane derivatives.